Hi,
On 03/11/2014 11:35 PM, Will Deacon wrote:
Hi Akashi,
On Fri, Feb 28, 2014 at 05:18:37AM +0000, AKASHI Takahiro wrote:
This patchset implements a function tracer on arm64.
There was another implementation from Cavium network, but both of us agreed
to use my patchset as future base. He is supposed to review this code, too.
The only issue that I had some concern on was "fault protection" code
in prepare_ftrace_return(). With discussions with Steven and Tim (as author
of arm ftrace), I removed that code since I'm not quite sure about possibility
of "fault" occurrences in this function.
The code is tested on ARMv8 Fast Model with the following tracers & events:
function tracer with dynamic ftrace
function graph tracer with dynamic ftrace
syscall tracepoint
irqsoff & preemptirqsoff (which use CALLER_ADDRx)
and also verified with in-kernel tests, FTRACE_SELFTEST, FTRACE_STARTUP_TEST
and EVENT_TRACE_TEST_SYSCALLS.
Prerequisites are:
* "arm64: Add regs_return_value() in syscall.h"
* "arm64: make a single hook to syscall_trace() for all syscall features"
patch
It looks like there might be some more dependencies that that. Do you have a
branch anywhere containing this series, along with all the dependencies so I
can have a play?
I think you saw the following messages:
> HOSTCC scripts/recordmcount
> /.../linux-aarch64/scripts/recordmcount.c: In function 'do_file':
> /.../linux-aarch64/scripts/recordmcount.c:350:7: error:
> 'EM_AARCH64' undeclared (first use in this function)
> /.../linux-aarch64/scripts/recordmcount.c:350:7: note:
> each undeclared identifier is reported only once for each function it appears
in
> /.../linux-aarch64/scripts/recordmcount.c:351:15: error:
> 'R_AARCH64_ABS64' undeclared (first > use in this function)
> make[2]: *** [scripts/recordmcount] Error 1
> make[1]: *** [scripts] Error 2
> make: *** [sub-make] Error 2
This happens when a header file, elf.h, on "your host machine" does not have
definitions of EM_AARCH64 nor R_AARCH64_ABS64 because "recordmcount" is a binary
utility on host(x86), not target. It is very likely for most distros.
(I mentioned this in the cover letter, but the description might not be clear.)
Possible solutions are:
1) Define both macros directly in scripts/recordmcount.c
2) Use perl version of recordmcount
Currently I take 1), but it is a workaround.
2) should work with my current patch, too. But you need to remove
HAVE_C_RECORDCOUNT
from arm64/Kconfig.
Which one do you prefer? I will include a fix for 1) in the next revision,
anyway.
Thanks,
-Takahiro AKASHI
Cheers,
Will
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